Singapore study debunks blood clot myth

SINGAPORE - Contrary to what was previously thought, Asians have a similar risk to Caucasians of developing blood clots after surgery.

A study done here and published in the Medical Journal Of Indonesia in February culled the medical records of more than 1,000 patients who underwent major orthopaedic or abdominal surgery at Khoo Teck Puat Hospital (KTPH) from 2011 to 2012.

It found that the incidence of venous thromboembolism, or blood clots that form in the veins, was 2.1 per cent.

This is higher than the under 1 per cent rate reported in Asian studies published 10 to 30 years ago, said Dr Ong Hean Yee, the study's principal investigator, who is also the public hospital's head of cardiology.

Instead, it falls within the 2.1 to 3.2 per cent rates reported in studies done in Europe and the United States, he added.

Venous thromboembolism is a disease that includes both deep-vein thrombosis (DVT) - a blood clot that forms in the veins in areas such as the leg or pelvis - and pulmonary embolism, a potentially fatal condition when the clot dislodges and travels to the lungs.

In the study, 1.3 per cent of the patients, or 14 of them, had DVT and 0.8 per cent, or nine patients, had pulmonary embolism. Three died from pulmonary embolism.

It also found that the incidence of venous thromboembolism was highest in people older than 75.

Patients in the study, aged between 16 and 109, had a median age of 65.

Dr Ong said the rising trend of venous thromboembolism is probably due to changing demographics - patients are now older and afflicted with more chronic conditions.

Dr Ng Heng Joo, a senior consultant at the department of haematology at Singapore General Hospital (SGH), has also noted a similar trend. His observation is based on published rates of DVT among hospitalised patients in SGH during three different periods. The rate of DVT per 10,000 admissions was 7.9 from 1989 to 1990, but rose to 15.8 from 1996 to 1997 and then to 45.3 from 2002 to 2003.

But Dr Ng does not expect the rates to continue climbing because heightened awareness of the condition means that "cases that are presented or developed in the hospital are not likely to be missed now".

To prevent clots from forming, one in 10 patients was given anticoagulants (blood thinners) after surgery, reported Dr Ong's study. Doctors have generally always been cautious about prescribing this medicine due to the risk of bleeding. But the study has prompted doctors at KTPH to be "more proactive", such that they are now prescribing anticoagulants to about one in five patients, said Dr Ong.

Orthopaedic and general surgeons at the hospital now refer to a form to calculate a hospitalised patient's risk of developing this complication.

It lists risk factors such as whether a patient would be bedbound for three or more days, have had heart or respiratory failure and previous blood clots, among other factors.

Patients can also turn to a new type of medicine that treats and prevents pulmonary embolism in adults, and also prevents DVT from cropping up again. Xarelto, approved by the Health Sciences Authority last December, is proven in clinical studies to have a low risk of interacting with other drugs, and does not require routine blood tests or dietary restrictions, unlike older types of anticoagulants.

IT executive Jason Hodges made the switch to this medicine, which is taken once a day, after a "frightening" episode last August that landed him in hospital.

He had suddenly become breathless at work, and a scan at Mount Elizabeth Novena Hospital revealed blood clots in both pulmonary arteries leading to his lungs. He was given the new medication at the hospital.

A year earlier in 2012, the 36-year-old Australian had been diagnosed with DVT after he sought help for a dull pain in his left leg. He took an anticoagulant for three months but the clots appeared to have travelled towards his lungs.

Besides taking the new medication regularly, his doctor has also advised him to lose weight.

Recalling his experience, Mr Hodges said: "I almost blacked out. I thought I had a heart attack."

joanchew@sph.com.sg

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